Signal strength in an antenna system is dependent on a number of factors, such as distance from the receiver to the transmitter, obstacles between the transmitter and receiver, signal fading, multipath reception, line of sight interference, Fresnel zone interference, radio frequency (RF) interference, weather conditions, noise, etc. Any one, or a combination, of these factors may result in poor connections, dropped connections, low data rates, high latency, etc. In order to mitigate these factors, a lobe of a radiation pattern for the transmitter antenna and/or the receiver antenna may be adjusted to direct the lobe between the receiver and the transmitter. Adaptive beam formers or beam steering automatically adapts the antenna response (of the transmitter, receiver, or both) to compensate for signal loss. In beam formers, interfering and constructing patterns may be used to change the shape and direction of the signal beam from multiple antennas using antenna spacing and the phase of signal emission from each antenna in an antenna array. Beam steering may change the directionality of the main lobe by controlling the phase and relative amplitude of the signal at each transmitter.
A metasurface, which is an artificial sheet material having electromagnetic properties that can varied on demand, may control reflection and transmission characteristics of EM wave. For example, a metasurface can be a two-dimensional periodical structure that contains electrically small scatterers with periodicity relatively small compared to an operating wavelength. A metasurface for purposes of beam steering system is described in “Two-Dimensional Beam Steering Using an Electrically Tunable Impedance Surface” by Sievenpiper et al. (IEEE Trans. On Antennas and Prop., Vol. 51, No. 10, pp 2713-2721, October, 2003). Sievenpiper discloses a two-dimensioning beam steering using an electrically tunable impedance surface loaded using varactor diodes. The use of varactor diode loading becomes impractical for high frequencies with a large surface where over hundreds of diodes are required. For communications applications, use of varactor diodes may be undesirable due to its nonlinearity which can induce undesirable noise due to passive intermodulation (PIM).